Winches may be used in connection with many applications. Examples include a ship anchor winch, a mooring winch, a ramp winch or a towing winch.
A winch can include a winch drum rotatable about an axis and used for spooling a spoolable medium such as a cable, a rope, a wire or a chain, for example. A winch may include a guiding member which is used to guide the spoolable medium during spooling in or spooling out of the spoolable medium. The purpose of the guiding member is to keep the angle between the spoolable medium extending out of the winch drum and the winch drum's axis of rotation within predetermined limits, such as around 90 degrees depending on the construction of the winch, during spooling of the spoolable medium. In order to do this, the guiding member moves between two end positions along an axis which can be arranged substantially parallel to the winch drum's axis of rotation. An example of a winch having a guiding member is disclosed in EP 1786716.
The operation of the guiding member may be manually controlled or automatic. In an automatic operation the winch guiding member can, for example, move automatically between the two end positions such that the angle between the spoolable medium extending out of the winch drum and the winch drum's axis of rotation is kept within suitable limits during spooling of the spoolable medium. For example, when the spoolable medium is being spooled in on the winch drum or out from the winch drum, the guiding member moves towards one of the two ends until a layer of the spoolable medium on the winch drum is spooled in or out and then changes its moving direction and starts to move towards another one of the two ends in order to spool in or out the next layer of the spoolable medium.
If the winch guiding member is driven with an electric motor via a screw engaging the guiding member, for example, the change of the moving direction of the guiding member may be accomplished by changing the direction of rotation of the motor or by reversing a gearbox or a similar device possibly mounted between the motor and the screw, for example. The change of the moving direction of the guiding member can be performed when the guiding member reaches the proximity of one of the two end positions. Such control of the moving direction of the guiding member involves a proximity of one of the two end positions being detected somehow. One possible solution is to use proximity switches or sensors at both end positions to detect that the guiding member has reached the proximity of one of the two end positions.
An issue related to the use of proximity switches or sensors is that in marine applications or similar environments, for example, harsh ambient conditions may pose an issue for reliable operation of the proximity switches or sensors.